The Notch gene was first described in 1917 when a strain of the fruit fly Drosophila melanogaster was found to have notched wing blades (Morgan, Am Nat 51:513 (1917)). The gene was cloned some seventy years later and turned out to be a cell surface receptor playing a key role in the development of many different cell types and tissues (Wharton et al., Cell 43:567-581 (1985)). Since then, the gene and its molecular mechanisms have been extensively studied. The generality of the Notch pathway manifests itself at different levels.
The Notch signaling pathway was soon found to be an evolutionarily conserved signaling mechanism from Drosophila to vertebrates and has been found to be involved in many cellular processes, such as differentiation, cell fate decisions, maintenance of stem cells, proliferation, and apoptosis, in various cell types during and after development (See review Artavanis, et al., Science 268:225 (1995)). Knockout mutations were found to be lethal in embryonic mice (Krebs et al. Genes & Dev 14(11):1343-52 (2000). The expression of mutant forms of Notch in developing Xenopus embryos interfere profoundly with normal development (Coffman, et al., Cell 73 (1993)). In humans, there have been several genetic diseases linked to Notch mutations (Artavanis-Tsakonas, et al. Science 284:770-776 (1999)).
Mammals possess four Notch proteins (designated Notch 1 to 4) and five corresponding ligands (Delta-1, -3, and -4, and Jagged-1 and -2). The mammalian Notch gene encodes a ˜300 kd protein that is cleaved during its transport to the cell surface and consequently exists as a heterodimer (NotchECD-NotchTMIC). The extracellular portion has many epidermal growth factor (EGF)-like repeats followed by three cysteine-rich Notch/Lin12 repeats (LN) (Wharton, et al, Cell 43:567 (1985); Kidd, et al, MoI Cell Biol 6:3431 (1986); Kopczynski, et al, Genes Dev 2:1723 (1988); Yochem, et al, Nature 335:547 (1988)). The amino-terminal EGF-like repeats participate in ligand binding, whereas the C-terminal part of the extracellular portion, including the Lin 12 repeats, prevent signaling in the absence of ligand. The signal induced by ligand binding is transmitted to the nucleus by a process involving proteolytic cleavage of the receptor and nuclear translocation of the intracellular domain (Notch-IC). After entering the nucleus, Notch-IC competes with inhibitory proteins and recruits coactivators, including mastermind-like (MAML) proteins, and acetyltransferases. The Notch-IC complex then binds to a transcription factor RBP-J to convert it from a transcriptional repressor to an activator. The few transcriptional factors identified so far vary in their nature and effects on the cell.
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) causes a type of stroke and dementia whose key features include recurrent subcortical ischaemic events and vascular dementia. Prominent manifestations on neuroimaging include extensive white matter lesions, lacunes and progressive brain atrophy. The disease is caused by highly stereotyped mutations that alter the number of cysteine residues in the extracellular domain of NOTCH3 (Joutel, A et al. 1997. The Lancet 350(9090):1511-5) which is predominantly expressed in vascular smooth muscle cells and pericytes of brain capillaries (Joutel, A et al. 2000. J Clin Invest 105 (5): 597-605). The two hallmark pathologies are extracellular NOTCH3 and GOM deposits, characteristically seen in close vicinity to the plasma membrane of vascular smooth muscle cells in the brain and peripheral vessels as well as of pericytes in the brain capillaries. NOTCH3 deposits are aggregates of the extracellular domain of NOTCH3 (Notch3ECD) and GOM are proteinaceous aggregates, with Notch3ECD being one important constituent (Joutel, A et al. 2000. J Clin Invest 105 (5): 597-605) (Ishiko et al. 2006 Acta Neurophatol 112(3):333-39) (Monet-Leprêtre et al. 2013. Brain: A journal of Neurology 136 (pt 6): 1830-45). Yet, today there are no therapies to prevent or halt the progression of the disease manifestations.
The inventors of the present invention have surprisingly found that anti-Notch 3 antibodies may be used in the treatment of CADASIL patients.